Commuting by subway -- or some other form of public transportation -- and commuting by car epitomize two dramatically different lifestyles in the United States.In the former, for example, an American might live in a high-rise building in a densely populated urban area. He rides an elevator to the street each morning and then descends via an escalator to an underground chamber, where he stands on a concrete slab until a crowded train comes along.When he boards that train, he is likely to stand, holding the metal rail above his head to make sure he does not fall when the...